#!python3
# -*- coding utf-8 -*-
__authoer__ = 'pxYe'

class Animal(object):
    def run(self):
        print('Animal is running...')

class Dog(Animal):
    def run(self):
        print('Dog is running...')

    def eat(self):
        print('Eating meat...')

class Cat(Animal):
    def run(self):
        print('Cat is running...')

class Tortoise(Animal):
    def run(self):
        print('Tortoise is running slowly...')

def run_twice(animal):
    animal.run()
    animal.run()

dog = Dog()
dog.run()

run_twice(Tortoise())

print(isinstance(dog, Animal))
print(isinstance(dog, Dog))
print(isinstance(dog, Cat))